Images from NASA's Mars Reconnaissance Orbiter are providing an advance peek at what the Phoenix Mars Lander will be running up against when it lands near the planet's north pole later this month: The spacecraft will be coming down in the middle of a spring thaw, and based on the pictures released this week, there just might be some Martian mini-tornadoes swirling through the scene.

©NASA / JPL-Caltech / MSSS

Arrows highlight two dust devils whirling across the landing area for the Phoenix Mars Lander, as seen from above by the Mars Reconnaissance Orbiter. Click on the image for a larger version.

Two of the twisters, known as dust devils, show up on an April 20 image of Phoenix's projected landing area, taken by MRO's Context Camera. The Martian whirlwinds are similar to the desert mini-twisters often seen on Earth - and have previously been caught on camera by the Mars Pathfinder lander as well as NASA's Spirit rover. You can watch a dust devil spin through Spirit's line of sight in this year-old video clip.

Phoenix will be landing just as the north polar region is warming up. This picture shows you what the terrain looked like a couple of months ago. The terrain was a honeycomb of dark soil, broken up by patterns of fractures still filled with frozen carbon dioxide.

In contrast, this picture from MRO's Color Imager shows that the frost has largely retreated from Phoenix's projected landing area. A wider view of the dust-devil scene reveals that bright spots of frost still lie within some of the region's craters, but those may soon be gone as well.

A Martian CO2 thaw isn't like a spring thaw on Earth: When carbon dioxide frost fades away, it sublimates directly into a gas and goes into the atmosphere.

The warming atmosphere fuels the formation of dust devils. As explained in this advisory from Malin Space Science Systems, the frequency of dust devils is expected to increase as the thaw proceeds. The full Context Camera strip, which takes in an area 18.6 miles wide and 195 miles long (30 by 314 kilometers) reveals plenty of dark streaks left behind by previous wind action. (Can you spot the two dust devils on the full strip?)

Mars' atmosphere is only 1 percent as dense as Earth's, so it's a matter of some interest among planetary scientists to find out how the wind can play such an active role on the Red Planet. Check out this archived report (and this one) for more about the Red Planet's powerful sand and dust.

To keep up with the latest as the Phoenix Mars Lander zooms toward its May 25 touchdown, check in with our "Return to the Red Planet" section as well as the home page for NASA's Mars Exploration Program.